如何删除重复项并在 pandas 上保持第一价值? [英] How do I drop duplicates and keep the first value on pandas?

问题描述

我想删除重复项并保留第一个值.要删除的重复项是A ='df'.这是我的数据

I want to drop duplicates and keep the first value. The duplicates that want to be dropped is A = 'df' .Here's my data

A   B   C   D   E
qw  1   3   1   1
er  2   4   2   6
ew  4   8   44  4
df  34  34  34  34
df  2   5   2   2
df  3   3   7   3
df  4   4   7   4
we  2   5   5   2
we  4   4   4   4
df  34  9   34  34
df  3   3   9   3
we  4   7   4   4
qw  2   2   7   2

结果将是

A   B   C   D   E
qw  1   3   1   1
er  2   4   2   6
ew  4   8   44  4
**df**  34  34  34  34
we  2   5   5   2
we  4   4   4   4
**df**  34  9   34  34
we  4   7   4   4
qw  2   2   7   2

推荐答案

创建帮助程序Series以便区分A列中的连续值，然后按(~)布尔掩码. org/pandas-docs/stable/generation/pandas.Series.duplicated.html"rel =" nofollow noreferrer> duplicated 与另一个掩码链接在一起以比较值df:

Create helper Series for distinguish consecutive values in A column and then filter by boolean indexing with inverted (~) boolean mask created by duplicated chained with another mask for compare value df:

s = df['A'].ne(df['A'].shift()).cumsum()
df = df[~((df['A'] == 'df') & (s.duplicated()))]
print (df)
     A   B   C   D   E
0   qw   1   3   1   1
1   er   2   4   2   6
2   ew   4   8  44   4
3   df  34  34  34  34
7   we   2   5   5   2
8   we   4   4   4   4
9   df  34   9  34  34
11  we   4   7   4   4
12  qw   2   2   7   2

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